[PATCH 6/7][TRIVIAL][resend] mm: cleanup page reclaim comment error

[PATCH 6/7][TRIVIAL][resend] mm: cleanup page reclaim comment error

[Wanpeng Li]

From: Wanpeng Li <liwp@linux.vnet.ibm.com>

Since there are five lists in LRU cache, the array nr in get_scan_count
should be:

nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
nr[2] = file inactive pages to scan; nr[3] = file active pages to scan

Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Rik van Riel <riel@redhat.com>

---
 mm/vmscan.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index eeb3bc9..ed823df 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1567,7 +1567,8 @@ static int vmscan_swappiness(struct scan_control *sc)
  * by looking at the fraction of the pages scanned we did rotate back
  * onto the active list instead of evict.
  *
- * nr[0] = anon pages to scan; nr[1] = file pages to scan
+ * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
+ * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
  */
 static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 			   unsigned long *nr)
-- 
1.7.9.5

Re: [PATCH 6/7][TRIVIAL][resend] mm: cleanup page reclaim comment error

[Johannes Weiner]

On Fri, Jun 15, 2012 at 09:19:45PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <liwp@linux.vnet.ibm.com>
> 
> Since there are five lists in LRU cache, the array nr in get_scan_count
> should be:
> 
> nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
> nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
> 
> Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Acked-by: Minchan Kim <minchan@kernel.org>
> Reviewed-by: Rik van Riel <riel@redhat.com>
> 
> ---
>  mm/vmscan.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index eeb3bc9..ed823df 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1567,7 +1567,8 @@ static int vmscan_swappiness(struct scan_control *sc)
>   * by looking at the fraction of the pages scanned we did rotate back
>   * onto the active list instead of evict.
>   *
> - * nr[0] = anon pages to scan; nr[1] = file pages to scan
> + * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
> + * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
>   */

Does including this in the comment have any merit in the first place?
We never access nr[0] or nr[1] etc. anywhere with magic numbers.  It's
a local function with one callsite, the passed array is declared and
accessed exclusively by what is defined in enum lru_list, where is the
point in repeating the enum items?.  I'd rather the next change to
this comment would be its removal.